1 files changed, 33 insertions, 0 deletions
diff --git a/solar.h b/solar.h
new file mode 100644
index 0000000..dc6e513
--- /dev/null
+++ b/solar.h
@@ -0,0 +1,33 @@
+/* solar.h */
+
+#ifndef _SOLAR_H
+#define _SOLAR_H
+
+#include <time.h>
+
+/* Model of atmospheric refraction near horizon (in degrees). */
+#define SOLAR_ATM_REFRAC  0.833
+
+#define SOLAR_ASTRO_TWILIGHT_ELEV   -18.0
+#define SOLAR_NAUT_TWILIGHT_ELEV    -12.0
+#define SOLAR_CIVIL_TWILIGHT_ELEV    -6.0
+#define SOLAR_DAYTIME_ELEV           (0.0 - SOLAR_ATM_REFRAC)
+
+typedef enum {
+	SOLAR_TIME_NOON = 0,
+	SOLAR_TIME_MIDNIGHT,
+	SOLAR_TIME_ASTRO_DAWN,
+	SOLAR_TIME_NAUT_DAWN,
+	SOLAR_TIME_CIVIL_DAWN,
+	SOLAR_TIME_SUNRISE,
+	SOLAR_TIME_SUNSET,
+	SOLAR_TIME_CIVIL_DUSK,
+	SOLAR_TIME_NAUT_DUSK,
+	SOLAR_TIME_ASTRO_DUSK,
+	SOLAR_TIME_MAX
+} solar_time_t;
+
+double solar_elevation(time_t t, double lat, double lon);
+void solar_table_fill(time_t date, double lat, double lon, time_t *table);
+
+#endif /* ! _SOLAR_H */